Technical data

Remove blockage. If
bypass fitted to system
pipework open up fully to
prove operation of boiler.
NO
15.0 Fault Finding
50
Fill system with water
and bleed out all air.
Replace PCB.
YES
NO
Dry-Fire Fault (L7 or L8)
YES
YES
NO
NO
Is the
system full of water ?
With
water flowing out of a
full open DHW tap, does
the Pump run ?
Wires from inline
connector to PCB
faulty.
Disconnect
primary flow switch
inline connector, with a tap
open, is there continuity
across flow switch ?
Remove blockage. Check
flow switch operation after
removing blockage before
replacing flow switch.
Remove
flow switch from boiler.
Is there a physical blockage
to the paddle within the
flow switch ?
Replace Flow Switch.
NO
YES
NO
YES
Mains Input
Transformer
Burner On
&
Fault Neons
Pump
Diverter Valve
Gas Valve
Modem PCB
Room Thermostat
Flow &
Return
Thermistors
Overheat
Thermostats
&
Flow Switches
&
Condensate Trap
Room Control
Display PCB
Fan
Unplug
the pump, is there 240V
at J?
Is there 240V at K?
Replace PCB.
Pump Fault (water in
pump housing
terminals ?).
Wiring from terminal
block to PCB faulty (or
water ingress).
With
water flowing out of
a fully open DHW tap, is
there continuity at L ?
Is there a
blockage in the system ?
NO
NO
YES
YES
YES
K
L
J
Plug from PCB to Pump
(when unplugged)